I grew up calling these “ladybugs”, too, but, technically, Harmonia axyridis, and other lady beetles, are not true bugs.
H. axyridis, also known as the harlequin lady beetle, Halloween lady beetle, Asian lady beetle, or multicolored Asian ladybeetle, is native to eastern Asia, but was introduced to Europe and North America in order to control pestiferous scale insects and aphids. It has done well in both geographical regions and is now quite common. In the UK, it has been jokingly labeled the “many-named ladybird” because its wide number of color and pattern variations has given rise to a large quantity of common names, including multivariate lady beetle, southern lady beetle, Japanese lady beetle, and “pumpkin ladybird”, which I just love.
A “generic” Asian lady beetle is primarily orange or red, with black spots on the elytra, and a white pronotum with variable black patterns. However, individuals can range from almost entirely orange to almost entirely black. The undersides of these beetles are almost always dark brown, and the legs are always reddish-brown, differentiating them from other, local, lady beetles which may have similar patterns.
Asian lady beetles aren’t generally harmful to humans, but they do stink unpleasantly when squashed (or even when irritated), and, in the winter, they aggregate together in groups which can damage household items (I once had a swarm of lady beetles short out the electricity in my home by clustering on a warm electric panel).